Interesting Facts

Dublin Tunnel is the largest ever civil engineering project in Ireland; only the electrification dam on the River Shannon at Ardnacrusha in the 1920s comes near.

The project employed 5000 people over the course of its construction delivering 7.5 million man hours. It is the longest road tunnel in an urban area in Europe.

2 million tonnes of rock and clay have been moved over the course of the project.

Much of the Tunnel is between 21 and 23 metres (7 storeys deep) below ground level, through hard limestone. There is approximately 10 metres of rock and 12 metres of boulder clay above the Tunnel.

The bored section of the Tunnels are between 10 and 15 metres apart, this changes in the cut and cover section (as the Tunnel rises to ground level) which is one structure separated by a central divide/wall.

Grainne, the hard rock tunnel boring machine, weighed 1800t, was 156m long, used 3.2Mw of electricity and cost approximately €27 million. It required 45 tunnellers per shift to operate.

Megan, the boulder clay boring machine, weighed 1100 tonnes was 60m long, used 400kw of electricity and cost €10million. It required 18 tunnellers to operate it on a shift basis.

Both tunnel boring machines were dismantled when they completed the first tube and reassembled in the return position - an operation that took three months for each machine. The same operation took place when they finished in 2004 before being moved off site.

The tunnel boring machines were guided by lasers with an allowed variation of + or – 6mm.

The project site was treated as a mineshaft until the machines broke through at the other end of the Tunnel. The Tara Mines Emergency Response Team provided search and rescue backup during that phase of the project. However it was never necessary to call them out.

During the construction of the cut-and-cover phase, Fairview Park contained an excavation the size of a cathedral, which is currently being reinstated and will revert to parkland. The Whitehall site had a hole 56 metres in diameter greater than the length of an Olympic size swimming pool (50m+) and equivalent to 7 storeys deep.

The project installed a crossing under the Dublin-Belfast railway line east of Fairview while the rail line remained live.

There are three new bridges within the Project:

Shantalla Bridge over the motorway

A new bridge over the Tolka River in East Wall

A new interchange and entrance into Dublin Port.

Alfie Byrne Road was raised by between 1.5 and 2 metres also providing a new entrance to East Point Business Park.

The project built 4,500 meters of boundary walls, all of which was either stone clad or fitted with acoustic panels.

The Project planted 40,000 trees and shrubs.

The Dublin Tunnel physical height 4.9m and operating height is 4.65 meters. The legal operating height clearance in Europe (as per EU directive 1996) is 4m with the exception of UK and Spain, which have none. Dublin Port Tunnel is higher than the Boston Big Dig (4.45m), Sydney's A6 (4.5m) and Madrid's Calle 30 (4.5m).
The regulation height in Ireland when the Tunnel was designed, through the public inquiry and tender stages were 4.25m. This legislation was revoked in July 2000 on procedures.

Over 98% of trucks leaving the Port will be able to use the Port Tunnel. This will greatly benefit Dublin City’s environment.

Note: Total bridge strikes per annum across Ireland's Rail network:

2001

2002

2003

2004

2005

2006 to April

79

55

136

122

203

52

Most struck bridges in Dublin (10-year period)

Custom House Quay

Sandwith Street (between Pearse and GCD)

South Lotts Road (between GCD and Lansdowne)

Erne St (between Pearse and GCD)

There are 50 traffic lights from Dublin Port to the Red Cow, via the Quays.
There are 3 traffic lights from Dublin Port to the Red Cow via the Port Tunnel.

There is a dedicated, specialist fire tender for the Port Tunnel and 200 Dublin Fire-fighters went to Switzerland to have specialist training for Tunnel incidents.

16 jet fans run the Tunnel's ventilation system and are capable of changing the air within minutes.

There have been several changes in legislation governing tunnels since the start of the project, and these have been incorporated into the current Tunnel’s safety features.